Digitizing devices are well known, and generally have a stylus or reticle (with cross-hair) that the user positions at discrete points or moves along a line or curve. The device provides output signals indicative of the position of the stylus or reticle, such as to a computer. Generally, the user is tracing an already-existing pattern to digitize the pattern for further manipulation in a computer.
U.S. Pat. No. 3,346,724, incorporated by reference herein, discloses an example of a random function tracer, for tracing lines on a map and for converting these tracings into Cartesian coordinates. The device utilizes certain features of a standard drafting machine in that there is a first arm section having one end that is pivotally connected to the table, a second arm section having one end pivotally connected to the other end of the first arm section. A stylus is provided at the other end of the second arm section. Potentiometers are provided at the two pivot points, at the one ends of the first and second arm sections. As the stylus is moved, the output of each potentiometer is proportional to the angle that one of the two arm sections has been rotated with respect to the other section and to the table.
Other examples of digitizing devices ar found in U.S. Pat. Nos. 4,419,672; 4,813,146; 4,973,800; 5,004,870; and 5,097,415, incorporated by reference herein.
Plotting devices are also known, and generally involve some kind or articulated arm or carriage arrangement which moves a pen or the like in a pattern, for example under the control of a computer.
U.S. Pat. No. 3,453,388, incorporated by reference herein, discloses a telescribing apparatus having separate transmitter (digitizing) and receiver (plotting) units. The receiver unit has servomotors for positioning a stylus, and also has an electromagnetic clutch operable to couple and decouple the receiver stylus shafts from the servomotor shafts. The clutch is disengaged to permit accommodation of drift in the transmitter and receiver units, and after a predetermined time delay is energized to couple said servomotor shafts to the styli shafts to permit unison movement of the transmitter and receiver styli.
Various elements of digitizers and plotters have been used as learning aids, for example to improve penmanship and drawing skills.
U.S. Pat. No. 4,464,118, incorporated by reference herein, discloses a device combining an optical image processing system with a speech synthesis system, wherein a drawing surface is provided in registration with the field of view of an optical imager. The user is requested, either visually via a display mounted on the housing of the device in proximity to the drawing surface, or verbally via speech synthesis electronics, to write or draw something on the drawing surface. When the user has completed the assignment by drawing indicia on the drawing surface, the image processing system, which includes an imager chip, a matrix memory in which signal data output from the imager chip is stored, and a data processor having an object recognition comparator, is actuated. The imager views the indicia as drawn by the user on the drawing surface and provides a signal data output indicative of the appearance of the indicia. The drawn indicia is then compared via the recognition comparator with the particular object configuration stored in memory and corresponding to the drawing instruction given to the user. Based upon the comparison, the speech synthesis system then gives an audible verbal response critiquing the writing or drawing of the user on the drawing surface and may be accompanied by a visual showing of the correct drawing on the display. As shown, for example, in FIG. 4 of this patent, the display (23) is separate and discrete from the drawing surface (10). Whereas indicia drawn by the user on the drawing surface are sensed in the imager (11), responses generated by the microprocessor are displayed on the separate display (23).
The system described in the above-referenced U.S. Pat. No. 4,464,118 is a didactic device for providing a learning experience and/or entertainment by serving as a learning aid to improve penmanship and drawing skills. The device contemplates a display mounted in proximity to the drawing surface. This requires the user to look at a pattern in one place, and draw (attempt to replicate) the pattern in another place on the overall device. This type of operation can be considered to by "copying", as opposed to "tracing". In contrast to such "copying", for "tracing", the user would create a pattern directly over an already-existing image.
U.S. Pat. No. 5,100,329 discloses a computer-assisted coaching method for helping students (users) in acquiring and developing the ability to perform an art or a skill. This is done by an interactive sequence wherein responses made by the student to inquiries and directives are digitized and compared with hidden idealized parameters and with previous responses.
U.S. Pat. No. 4,506,336 discloses a point location and graphics display apparatus which uses a rolled, flexible steel tape having a stylus at its outer extremity. An angle encoder and a linear encoder, respectively, are driven by rotation of the tape (via roller sprockets engaging the tape), and provide signals to a computer which digitizes and supplies those signals to a display.
U.S. Pat. No. 4,633,416 discloses a video image creation system which simulates a drafting tool. Images are created under manual control, which effectively defines the coordinates of the artist's (user's) implement at any given time. A processor receives the incoming image data, and previously derived data from a frame store, and modifies this data in dependence on a parameter available from another store. The parameter controls the contribution made from any adjacent, previously-created parts of the image, and can be such as to simulate different pencil or brush shapes or types of paint, for example. Additional facilities such as pressure sensitivity and blurring can be provided.